Analysis of water control in an underground mine under strong karst media influence (Vazante mine, Brazil)

Ninanya, Hugo; Guiguer, Nilson; Vargas, Eurípedes A. Jr; Nascimento, Gustavo; Araujo, Edmar; Cazarin, Caroline L.

Analysis of water control in an underground mine under strong karst media influence (Vazante mine, Brazil) | Analyse du contrôle de l’eau dans une mine souterraine sous forte influence d’un milieu karstique (mine de Vazante, Brésil) Análisis del control del agua en una mina subterránea bajo fuerte influencia del medio kárstico (mina Vazante, Brasil) 强烈岩溶介质影响下地下矿控水分析(巴西Vazante矿) Análise do controle da água em uma mina subterrânea sob forte influência do meio cárstico (mina Vazante, Brasil)

2018

This work presents analysis of groundwater flow conditions and groundwater control measures for Vazante underground mine located in the state of Minas Gerais, Brazil. According to field observations, groundwater flow processes in this mine are highly influenced by the presence of karst features located in the near-surface terrain next to Santa Catarina River. The karstic features, such as caves, sinkholes, dolines and conduits, have direct contact with the aquifer and tend to increase water flow into the mine. These effects are more acute in areas under the influence of groundwater-level drawdown by pumping. Numerical analyses of this condition were carried out using the computer program FEFLOW. This program represents karstic features as one-dimensional discrete flow conduits inside a three-dimensional finite element structure representing the geologic medium following a combined discrete-continuum approach for representing the karst system. These features create preferential flow paths between the river and mine; their incorporation into the model is able to more realistically represent the hydrogeological environment of the mine surroundings. In order to mitigate the water-inflow problems, impermeabilization of the river through construction of a reinforced concrete channel was incorporated in the developed hydrogeological model. Different scenarios for channelization lengths for the most critical zones along the river were studied. Obtained results were able to compare effectiveness of different river channelization scenarios. It was also possible to determine whether the use of these impermeabilization measures would be able to reduce, in large part, the elevated costs of pumping inside the mine.

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